Interfacial engineering of Co–MnO nanocubes on mycelium carbon enabling synergistic bifunctional water splitting

Although remarkable progress has been achieved in electrocatalytic water splitting, the design of highly efficient bifunctional catalysts remains a significant challenge, mainly because of the slow kinetics of the oxygen evolution reaction (OER) and the limited stability of non-precious metal catalysts. This work presents a novel heterojunction catalyst consisting of Co–MnO nanocubes anchored on nitrogen-doped graphitic carbon derived from carbonized Ganoderma lucidum mycelium (CGLM), synthesized via an ion-exchange-coupled pyrolysis strategy. The unique fibrous entanglement morphology of CGLM offers ideal anchoring sites for catalytic centers, while preserving its intrinsic three-dimensional porous architecture to establish a continuous conductive network. This structural enhances electron transport efficiency and promotes stable immobilization of Co–MnO nanocubes (Co–MnO -2 /CGLM). Extensive experimental and theoretical investigations demonstrate that the Co–MnO -2 heterogeneous interface induces charge redistribution, synergistically optimizes the hydrogen adsorption free energy (Δ G H  = −0.15 eV), and reduces the OER energy barrier, with a rate-determining step of Δ G 4  = 1.69 eV. The catalyst demonstrates remarkable bifunctional activity in alkaline media, exhibiting overpotentials of 105 mV for hydrogen evolution reaction (HER) at 10 mA cm −2 and 250 mV for OER at 50 mA cm −2 . Notably, the assembled electrolytic cell (Co–MnO -2 /CGLM||Co–MnO -2 /CGLM) achieves a voltage of only 1.61 V (50 mA cm −2 ) in overall water-splitting tests and maintains excellent durability, with negligible change in current density during prolonged operation. This study highlights the synergistic effect of heterogeneous structure engineering combined with biomass-derived carbon substrates in reducing reaction barriers and facilitating charge transfer, offering novel perspectives on the design of cost-effective electrocatalysts for sustainable energy conversion.